Compare proportions between 2 groups

A function to facilitate 2 group permutation tests for a categorical outcome variable

compareProportion(formula, data = NULL, ...)

Arguments

formula	a formula
data	a data frame in which x is evaluated if x is a formula.
…	other arguments

Value

the difference in proportions between the second and first group

Note

This function is now defunct. Use diffprop() instead.

Examples

if (require(mosaicData)) {
  data(HELPrct)
  # calculate the observed difference
  mean(homeless=="housed" ~ sex, data=HELPrct)
  obs <- diffprop(homeless=="housed" ~ sex, data=HELPrct); obs
  # calculate the permutation distribution
  nulldist <- do(100) * diffprop(homeless=="housed" ~ shuffle(sex), data=HELPrct)
  histogram(~ diffprop, groups=(diffprop>= obs), nulldist,
    xlab="difference in proportions")
}